Increasing evidence has shown that diabetes-associated cognitive impairment is correlated with mitochondrial dysfunction and resultant synaptic injury as well as brain insulin resistance. Cardiotrophin-1 (CT-1), a regulator of energy metabolism, has been shown to exhibit impressive neuroprotective effects. In this study, we evaluated the effects of CT-1 on brain pathological features in intracerebroventrical-streptozotocin (ICV-STZ)-treated mouse model, and explored its potential mechanisms. STZ was injected twice (3 mg/kg, ICV) on alternate days (day 1 and day 3) in mice. Daily treatment with CT-1 (1 μg/day, ICV) starting from the first dose of STZ for 14 days showed that CT-1 significantly improved learning and memory deficits, alleviated mitochondrial dysfunction, and increased synaptic density in the CA1 region of the hippocampus in ICV-STZ-treated mice. Moreover, CT-1 significantly enhanced insulin signaling pathway in the hippocampus of ICV-STZ-treated mice when compared with the control. However, all the protective effects including biochemistry, pathological changes and cognitive function could be blocked by an ICV injection of Compound C, a specific AMPK inhibitor. Taken together, these results suggested that CT-1 improves pathological changes and cognitive impairments via AMPK activation in ICV-STZ mice.